Method and apparatus for making expanded metal sheets

ABSTRACT

A method of making an expanded metal sheet comprising the steps of stamping successive adjacent strips of a plain metal sheet to sever each strip from the plain sheet except at a plurality of spaced apart positions, and deforming the metal of the strip intermediate those positions characterized in that two separate dies of mutually different profile are alternately utilized for the steps.

United States Patent 11 1 North Oct. 15, 1974 [54] METHOD AND APPARATUS FOR MAKING 3,570.086 3/1971 Stonc 29 6,:

EXPANDED METAL SHEETS FOREIGN PATENTS OR APPLICATIONS Inventor! Mark North; New Lambton, 1,127,856 4 1963 Germany 29/62 Austraha l,l27,857 4/1963 Germany 29 62 [73] Assignee: John Lysaght (Australia) Limited,

New South wales, Australia Przmary ExammerAndrew R. Juhasz Assistant Examiner-Leon Gilden [22] Flled: 1972 Attorney, Agent, or Firm-Stev'ens, Davis, Miller & 21 Appl. No.2 301,859 Moshe/r [30] Foreign Application Priority Data [57] ABSTRACT Nov. 3, 1971 Australia 6877/71 A method of making an expanded metal Sheet prising the steps of stamping successive adjacent strips [52] US. Cl. 29/62 of a Plain metal Sheet to Sever each strip from the 51 int. Cl B2ld 31/02 Plain Sheet except at a plurality of Spaced apart P [58] Field of Search 29/6.l 6.2 29%.. an f9 h metal of the Strip intermediate those positions characteiizeil in Hat two separate [56] References Cited dies of mutually different profile are alternately uti- UNITED STATES PATENTS d for the 3,431,613 3 1969 Acker et al. 29 62 2 Claims, 5 Drawing Figures PAIENTEDBm 1 51914 SHEET 10F 2 FIG, 1,

FIG.3.

PAIENTEDnm 1 5 m4 SHEET 2 BF 2 FIG. 5.

METHOD AND APPARATUS FOR MAKING EXPANDED METAL SHEETS This invention relates to the manufacture of expanded metal sheets.

Hitherto such sheets have been made by successively stamping edge margins of a plain metal sheet to convert each edge margin into an undulating strip united at spaced apart locations to the immediately previously stamped strip along one edge and to the body of the plain sheet along its other edge. Between each stamping operation the stamping die is shifted laterally of the plain sheet (that is to say longitudinally of the edge margin to be stamped) by a distance equal to a halfpitch of the undulations in the strip, thus ensuring that the troughs of the undulations of each stamped strip are united to the crests of the undulations of the immediately previously stamped strip.

The production of expanded metal sheets as briefly described above is well known. The sheets produced by such known processes are necessarily uniform in pattern throughout the sheet because each strip is stamped by the same die and because of the need for uniformity of the undulation pitch to suit the distance of lateral movement of the die between each stamping operation.

An object of the present invention is to enable greater variation in pattern, either by variation in the undulous configuration of adjacent strips or by variation of the undulation pitch at different positions along the strip or by both.

The invention achieves that object by providing a method of making an expanded metal sheet comprising the steps of stamping successive adjacent strips of a plain metal sheet to sever each strip from the plain sheet except at a plurality of spaced apart positions and to deform the metal of the strip intermediate those positions characterized in that separate dies of mutual ly different profile are utilized for each of any two consecutive steps.

The invention also consists in apparatus for effecting the above described method comprising means to feed a metal sheet intermittently to at least two dies each adapted to stamp a strip of said sheet to sever the strip from the sheet except at a plurality of spaced apart positions and to deform the metal of the strip intermediate those positions and means to operate said dies to cause each to stamp a predetermined selection of said strips, the arrangement being such that no one die operates on two adjacent strips.

According to some embodiments of the apparatus of the invention there are as many stamping stations as there are dies and the dies are respectively associated with the stamping stations. In such instances the sheet is fed through the various stamping stations in sequence and, in the case of two dies for example, the upstream die may operate on a double width strip of the sheet, a half or other fraction of which is subsequently operated on by the downstream die.

However, in preferred embodiments of the invention all of the dies operate at a single stamping station and the apparatus includes means to shift the dies into and out of the stamping station in a predetermined sequence.

By way of example, an embodiment of the invention is described hereinafter with reference to the accompanying drawings.

FIG. 1 is a diagrammatic elevation of the punching die of a conventional expanded metal sheet stamping apparatus.

FIG. 2 is a diagrammatic sectional view taken on line 22 of FIG. 1.

FIG. 3 is a view similar to FIG. 1 of an apparatus according to the invention.

FIG. 4 is a diagrammatic sectional view taken on line 4-4 of FIG. 3.

FIG. 5 is a non-diagrammatic view similar to FIG. 4.

FIGS. 1 and 2 illustrate a conventional apparatus comprising fixed die 7 and a single punching die 8. The punching die 8 rises and falls through return and working strokes respectively and at the top of each return stroke is oscillated endwisely so that it is positioned as shown by full lines (FIG. 1) during each alternate working stroke and as shown by broken lines during each of the other working strokes. Thus, a workpiece 9 fed intermittently across the fixed die 7 is formed into a conventional expanded metal sheet 10.

Such an expanded sheet is uniform in pattern throughout.

FIGS. 3 and 4 illustrate apparatus according to the invention comprising a fixed die 11 and two punching dies 14 and 15. The dies 14 and 15 rise and fall but instead of a translational oscillation they are caused to oscillate rotationally to bring each die 14 or 15 alternately into the vertical plane during each working stroke.

The I IGB embodiment utilizes punching dies 14 and 15 which are not the same as each other so that a nonuniform pattern is produced in the finished expanded sheet. FIG. 5 illustrates the FIGS. 3 and 4 embodiment of the invention in more detail. The apparatus comprises a work sheet supporting table 16 with a bladelike fixed bottom die 17 or anvil set in its edge, a worksheet hold-down clamp 18 adapted to clamp a worksheet 19 against an upper face of the bottom die 17, means to advance the work-sheet 19 (not shown) and a reciprocating ram 20 above and outboard of said edge all of substantially conventional character. The operating mechanism of the apparatus is conventional insofar as it synchronizes the operation of the ram 20 hold-down clamp 18 and sheet feed mechanisms to obtrude a fresh strip of the work-sheet 19 beyond the edge of the bottom die 17 during each up-stroke of the ram 20 in preparation for a stamping operation thereon during the next down-stroke of the ram 20.

In conventional apparatus an upper blade-like die is mounted on the ram so as to extend downwardly therefrom in the manner of a shear blade adaptaed to coact with the bottom die. The upper die is mounted on the ram in a'manner permitting longitudinal translatory reciprocation of the upper die.

In accordance with the illustrated embodiment of the invention, however, a die holder 21 is secured to the under-face of the ram 20 by means which permit the die holder to be swung about an axis extending longitudinally of the holder. To that end, the die holder 21 may be attached to a fulcrum shaft 22 of which an upper part is horned in a part-cylindrical groove formed in the bottom end of the ram 20. The fulcrum shaft 22 may be held in place by two or more hook shaped retainers 23.

The die holder 21 provides locations for two bladelike punching dies 24 and 25 respectively and means are provided to swing the die holder 21 about the axis of its fulcrum shaft 22 to bring the dies 24 and 2S alternately into an operative position relative to the bottom die 17.

The die holder 21 may be swung to and fro to bring the dies 24 and 25 into and out of their operative position by means, for example, of a toggle arm 26 projecting from a toggle shaft 27 mounted on a bracket 28 projecting from the ram and with its free end connected by a toggle link 29 to the die holder 21. The toggle arm 26 may be rocked to and fro by means of a cam follower rod 30 pivoted to the free end of a lever arm 31 projecting from the toggle shaft 27 and extending to thecam in the operating mechanism of the apparatus which in conventional apparatus is similarly utilized to effect longitudinal reciprocation of the upper die.

The two operative positions of the die holder 21 may be determined on one hand by a screw adjustable stop 32 and on the other hand by virtue of the full straightening of the toggle.

If necessary, the hold-down clamp 18 may be shaped (as shown) so as not to foul the die holder 21 or the die 25 as they swing to and fro.

I claim:

1. A method of making an expanded metal sheet comprising the steps of stamping successive adjacent strips of a plain metal sheet to sever each strip from the plain sheet except at a plurality of spaced apart positions, and deforming the metal of the strip intermediate those positions characterizedin that separate dies of mutually different profile are utilized for each of any two consecutive steps.

2. A method according to claim 1 wherein two dies are used alternately. 

1. A method of making an expanded metal sheet comprising the steps of stamping successive adjacent strips of a plain metal sheet to sever each strip from the plain sheet except at a plurality of spaced apart positions, and deforming the metal of the strip intermediate those positions characterised in that separate dies of mutually different profile are utilised for each of any two consecutive steps.
 2. A method according to claim 1 wherein two dies are used alternately. 